نتایج جستجو برای: 14 aryl 14h dibenzoxanthene
تعداد نتایج: 373509 فیلتر نتایج به سال:
We report the first atomistic level description of the handedness inversion mechanism for helical arylamide foldamers. The key process in the handedness inversion is the simultaneous unfolding and folding of two adjacent aryl-aryl linkages, propagating from a helix terminus along the strand. Intermediates along the inversion pathway have a common feature - a single unfolded aryl-aryl linkage (t...
Many directing group containing arenes can now be arylated or alkylated under palladium, rhodium, or ruthenium catalysis.1 Even arenes lacking traditional directing groups can be functionalized representing the most atom-efficient method for creation of arylaryl bonds.2 However, in this case, regioselectivity issues often are unsolved. An exception can be found in recent elegant work by Fagnou ...
Abstract In this paper, enthalpies of formation and electronic structures long period stacking ordered phases in ternary Mg-Zn-Y alloys are calculated by first-principles. Through calculations the formation, it was found that 10H phase 14H negative, enthalpy less than phase. It shows both can form stable structure. The energy transformation show is more analysis structure difference between str...
An efficient and straightforward method for one-pot synthesis of aryl azides from the corresponding amines, employing tributylstannyl azide as transfer reagent of N3 group is described. In this procedure diazotization of aryl amines occurs under mild conditions using tert-butyl nitrite (t-BuONO) and p-toluenesulfonic acid (TsOH). A variety of substituted aryl amines, with both electron-withdraw...
Aminocarbonylation of aryl halides is one of the most useful methods in amide synthesis, but nitroarenes have not been used as a nitrogen source in this method even though they are more economical and accessible than anilines. Reported here is the development of nickel catalysis for the first three-component reactions of aryl halides, Co2(CO)8, and nitroarenes under reductive conditions to prod...
A conceptually new, simple and practical method for the syn-nucleophilic displacement of aryl and vinyl epoxides and aryl aziridines with (substituted) phenols, using aryl borates as activating nucleophiles under neutral conditions, is reported.
A silver-mediated cross-coupling of trifluoromethoxide with aryl stannanes and arylboronic acids to give aryl trifluoromethyl ethers is reported. This is the first report of a transition-metal-mediated C(aryl)-OCF(3) bond formation.
The transition-metal-catalyzed amination of aryl halides has been the most powerful method for the formation of aryl amines over the past decades. Phenols are regarded as ideal alternatives to aryl halides as coupling partners in cross-couplings. An efficient palladium-catalyzed formal cross-coupling of phenols with various amines and anilines has now been developed. A variety of substituted ph...
The first allylic carbonylation reaction of allylic acetates with aryl boronic acids under carbon monoxide has been developed. Using Pd-PCy3 as a catalyst, a wide spectrum of allylic acetates was carbonylated in the presence of various aryl boronic acids, affording α,β-unsaturated aryl ketones in good to excellent yields. Preliminary studies indicate that carbon monoxide always inserts at the l...
Phosphine-free Suzuki-Miyaura cross-coupling in aqueous media enables access to 2-C-aryl-glycosides.
A general strategy for the synthesis of 2-aryl-glycals and their elaboration to 2-C-aryl-α-glycosides and 1,5-anhydro-2-C-aryl-2-deoxy alditols are described. The use of reliable, efficient phosphine-free Suzuki-Miyaura cross-coupling of 2-iodoglycals in aqueous media as a key step proceeds with complete regioselectivity at C-2 and enables access to 2-aryl-glycals with different configurations ...
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